linux-kernel - Re: [PATCH] crypto: x86/aesni - Update aesni_set

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Date: Tue, 12 Mar 2024 08:03:25 -0700
From: "Chang S. Bae" <chang.seok.bae@...el.com>
To: Ard Biesheuvel <ardb@...nel.org>
CC: <linux-kernel@...r.kernel.org>, <linux-crypto@...r.kernel.org>,
	<herbert@...dor.apana.org.au>, <davem@...emloft.net>, <ebiggers@...nel.org>,
	<x86@...nel.org>
Subject: Re: [PATCH] crypto: x86/aesni - Update aesni_set_key() to return void

On 3/12/2024 12:46 AM, Ard Biesheuvel wrote:
> On Mon, 11 Mar 2024 at 22:48, Chang S. Bae <chang.seok.bae@...el.com> wrote:
>>
>> @@ -241,7 +241,7 @@ static int aes_set_key_common(struct crypto_aes_ctx *ctx,
>>                  err = aes_expandkey(ctx, in_key, key_len);
>>          else {
>>                  kernel_fpu_begin();
>> -               err = aesni_set_key(ctx, in_key, key_len);
>> +               aesni_set_key(ctx, in_key, key_len);
> 
> This will leave 'err' uninitialized.

Ah, right. Thanks for catching it.

Also, upon reviewing aes_expandkey(), I noticed there's no error case, 
except for the key length sanity check.

While addressing this, perhaps additional cleanup is considerable like:

@@ -233,19 +233,20 @@ static int aes_set_key_common(struct 
crypto_aes_ctx *ctx,
  {
         int err;

-       if (key_len != AES_KEYSIZE_128 && key_len != AES_KEYSIZE_192 &&
-           key_len != AES_KEYSIZE_256)
-               return -EINVAL;
+       err = aes_check_keylen(key_len);
+       if (err)
+               return err;

         if (!crypto_simd_usable())
-               err = aes_expandkey(ctx, in_key, key_len);
+               /* no error with a valid key length  */
+               aes_expandkey(ctx, in_key, key_len);
         else {
                 kernel_fpu_begin();
-               err = aesni_set_key(ctx, in_key, key_len);
+               aesni_set_key(ctx, in_key, key_len);
                 kernel_fpu_end();
         }

-       return err;
+       return 0;
  }

Thanks,
Chang